21312432400 has 180 divisors, whose sum is σ = 60005135988. Its totient is φ = 7252869120.

The previous prime is 21312432371. The next prime is 21312432439. The reversal of 21312432400 is 423421312.

It can be written as a sum of positive squares in 6 ways, for example, as 1302632464 + 20009799936 = 36092^2 + 141456^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 2681232 + ... + 2689168.

Almost surely, 2^21312432400 is an apocalyptic number.

21312432400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21312432400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30002567994).

21312432400 is an abundant number, since it is smaller than the sum of its proper divisors (38692703588).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21312432400 is a wasteful number, since it uses less digits than its factorization.

21312432400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8106 (or 8088 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 22.

Adding to 21312432400 its reverse (423421312), we get a palindrome (21735853712).

The spelling of 21312432400 in words is "twenty-one billion, three hundred twelve million, four hundred thirty-two thousand, four hundred".